sqlalchemy 判断表是否存在_sqlalchemy 对已存在的数据库表格进行操作

import MySQLdb

import sqlalchemy

from sqlalchemy import create_engine

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String

from sqlalchemy.orm import sessionmaker

from sqlalchemy import create_engine, Table, MetaData

conn=MySQLdb.connect(host="localhost",user="root",passwd="123456")

cur=conn.cursor()

db="test"

if cur.execute('show databases like %s',(db,)):

engine = create_engine("mysql+mysqldb://root:123456@localhost/%s?charset=utf8"%(db),encoding='utf-8')

else:

print("there is no database of %s"%(db))

exit()

Base = declarative_base() #生成orm基类

Session_class = sessionmaker(bind=engine) #创建与数据库的会话session class ,注意,这里返回给session的是个class,不是实例

Session = Session_class() #生成session实例

metadata = MetaData()

teacher_1= Table('teacher_1', metadata, autoload=True, autoload_with=engine)

class_1= Table('class', metadata, autoload=True, autoload_with=engine)

course= Table('course', metadata, autoload=True, autoload_with=engine)

tables=engine.table_names()#显示所有的表

print(tables)

Session.execute(teacher_1.insert(),{"tname":"angel"})#增加新数据

Session.execute(teacher_1.delete().where(teacher_1.c.tid==3))#删除数据

Session.execute(teacher_1.update().where(teacher_1.c.tid==2).values(tname='wupeiqi'))#修改数据

teahcer_obj1=Session.execute(teacher_1.select().where(teacher_1.c.tid>1).where(teacher_1.c.tid<10))#查询数据

teahcer_obj = Session.query(teacher_1).filter_by(tid=2).all()#查询数据

print(teahcer_obj)

print(teahcer_obj1.fetchall())

Session.commit()